What is the cause of biodiversity? The answer lies in the concept of multilevel and hierarchical organisation by which shared components are associated to form stable structures of ever-increasing size and complexity, whose properties cannot be deduced through the study of the single components. In the human body, for example, the association of macromolecules results in the formation of subcellular organelles, which, in turn, join to give rise to cells. The association of cells gives rise to tissues, whose assembly results in the creation of organs. Our body is thus a multilevel, hierarchical system, or rather an association of subsystems within a system. The subdivision into two sections – cell biology and tissue biology – and the graphics used make this text a useful and flexible study aid. It complies with the new teaching requirements in several spheres of university study – biotechnology, biological sciences and environmental sciences – where the approach to and the space devoted to the study of cell biology and tissue biology can vary.

The web platform (Virtual Campus) represents a breakthrough in field of Cytology and Histology texts and presents a rich catalogue of interactive educational materials. To navigate through these resources, students can take advantage of guided and interactive courses presented in a lesson format. The platform’s contents include: • interactive views of histological slides using a virtual microscope; • commentated videos; • online lectures and workshops; • predefined evaluation tests and self-assessments.